Among other solution xrdp in my opinion is one of the best.
Link to this project is: http://www.xrdp.org/
First of all does not require user logged on system and we can connect via this solution via any Windows machine or Linux(,e.g.Remina)
Installation is pretty easy
apt-get install xrdp
Xrdp is using vnc4server so you have to approve installation of this packet.
Below some screenshoots during workign via xrdp
from Windows machine
from Debian machine
dzbanek 2012-11-26